Radio receiving apparatus



Jan. 30, 1940.

VORIE 2,188,490

RADIO RECEIVING APPARATUS EMF OSC

CONTROL Filed Aug. 13, 1937 DISCRIMINA'IUR AMP OSC

- M IXER AMP 2 Sheets-Sheet 1 MU'IIN G CONTROL anmc/wto r/ INNOKENT N. VCR/E Jan. 30, 1940.

I. N. VORIE RADIO RECEIVING APPARATUS Filed Aug. 13, 1937 2 Sheets-Sheet 2 AOKHZOU omvrw dwo UmO MMQEH mz woaomamn INNOKENT' N VOE/E SHW Patented Jan. 30, 1940 fv UNITED STATES PATENT OFFICE 2,1ss,49o I I l a I n mo RECEIVING APPARATUS InnokentN. Vorie, Tonawanda, N. Y., assignor to Colonial Radio Corporatiom-Buflalo, N. Y., a

corporation'of New York I v ncan n u ust "1a, 1937, Serial No. 158,844

11 Claims. (c1. 251F207 This invention relates to radio receiving apparatus and more particularly to improvements in radio receivers of the type disclosed 'in MatZner Reissue Patent'No. 18,796, in which a flashing stop 5 signal is provided, showing when the tuning apparatus has arrived at the proper position to select any one or more of a number of chosen stations for which the receiverlias previously 7 been adjusted to'give such a signal. v 10 For the purpose of thisdescription, such stations are herein termed flash stations, because they may be selected by a flash signalof the receiver receiver.

The increasing power and crowding of transmitting stations in the ether channels, together 25 overcome to a very considerable degree by'certain inventionsfor which other patent applications have been or are being filed by the assignee of this application, in which there is disclosed a flash tuning receiver of the super-heterodyne type, in

30 which the mechanism of the receiver may be keyed or adjusted for flash tuning to a consider-1 able number of stations, and which is mute, or

substantially so, between flash tuning. stations;

that is to say, the receivenwhe'n adjusted for, 35 flash tuning operation, will respond only to flash tuning stations, and when being tuned from one flash tuning station to another, will not respond to intervening stations forwhich the mechanism has not been keyed, not to static, or power 40 line noises.

It is an object of this mvention to ,provide a receiver of the type referred to, in which the muting system is considerably simplified.

It is a further object of this invention to pro- I 45 vide a receiver in which the muting system requires no relays for the operation ofadditional circuits, other than that closed by theflash mechanism of the dial itself.

It is a further object of this invention to pro- 50 vide a receiver in which the closure of the dial control contacts for indicating a flash station in themselves serve to voice the receiver, with- T out requiring the operation of supplemental contacts to-operate or modify other circuits. 55 It is a further object of this invention to prowithout reference to logs, newspaper, guides, or the like, after having once been adjusted or keyed in the flash mechanism oi the videa receiver. which the receiveris controlled from the mute state, between flash -tuning'sta tions, to the *voiced state when .tuned to a flash station, without the operation of'any con-"'- tacts other than the dial controlcontactswhich l r serve to give the flash signal that the receiver is tuned to a flash station. v c

It is still a iurtherj object of this invention to provide muting mechanism for flash tuning-:re-

ceivers, which-shallbe more economical tornanul0 facture and install than the'previously known systems, without sacrificing operating efliciency in any respect.

A further object ofthis invention" to provide? .a pair of lamps, one of whichbe illuminated only 16 when a desired station is tuned in, whilethe other I is lighted whenever the receiver isin-"use but not tuned 'toa desiredstation.

Still other objects and advantages of my-in- ,vention will be apparent from the specification. 20X

The features of novelty which I believe to be. characteristic of my invention are set forthwith particularity in the appended .claims.- My; invention itself however, both as to its fundamental principles and as to its particular embodiments,

will best be understood by reference to the speci ficationa nd accompanying drawings, in which;

Fig. 1 is-aschernatic or block "diagram of areceiver in accordance with my invention, and I Fig. 2 is a detailed circuit diagram of the improved muting system in accordance withmy invention, showing so much of the circuits of the radio receiver as are necessary to an understand,- ing of my invention. l

My invention is disclosed herein, bywayo'f example, as embodied'in'a super-heterodyne receiver arranged tooperate from a commercial source of alternating current. It will be understood, however, that this by way of. example, ascertain of the principles of my inventionf'may be applied .4 I I to battery operated receivers, as well as those not involving the super-heterodyne principle.

My invention is illustrated applied to a receiver having'a signal selector dial of-theclock type in which a pointer moves over a dial, all of Which'is exposed to view, with means for mount ing tabs showing thecallletters of the'various I stations, and a travelling flash signal light mount} ed in position to selectively illuminate anyone only of the call letter tabsat atime; whichreceiver is provided .with means for controlling-the oscillator frequency to provide for exact and I a precise tuning of the desiredcsignal over a COIl-E' siderably greater dial setting than would other wise be possible, and in accordance "with my in- 1 5' the extent desired,

vention has simple and improved means for preventing or reducing any response of the loud speaker except when the receiver is tuned to a flash station (herein called muting). Referring now more particularly to Fig. 1,

I designates any suitable form of antenna from which a signal voltage is drawn, and which may be amplified at its own frequency in amplifier 2 if desired, and with which there may be associated selecting circuits of any desired type. After the desired amount of amplification, the signals are fed to a mixer or first detector tube 3 and mixed there with beat or heterodyne currents from oscillator 9, and from which they emerge at a 10V!- er frequency (so-called beat or intermediate frequency) and are then amplified by amplifier to the desired extent at the beat frequency.

These further amplifiedgsignals are then applied to a discriminator and detector network 5. At this point, it suffices to note that the discriminator and detector network has a pair of output circuits, to one pair of which it supplies audio frequency or voice currents derived from a seconddetection or demodulation of the signal, and to the other of which it supplies a direct current voltage, herein termed oscillator frequency control voltage Ed, the magnitude of whichis proportional, within limits, to the deviation of the intermediate or beat frequency being received, from the calculated or designvalue, and the sign of which corresponds to the direction of such deviation. Since the said network is not, per se, a part of my invention, it is not herein described in detail.

This oscillator control voltage is applied to an oscillator frequency control circuit, operating in a mannerto cause a change'oi the oscillator frequency in the direction required for correction of mistuning or drift in the receiver by an amount such as to keep the intermediate frequency always at or very near the predetermined value for any particular station.

- 'The audio frequency output of the detector anddiscrimin'ator network is supplied to asuitable audio frequency'amplifler which may comprise tubes 6 and l, and,'after amplification to to a suitable signal indicator such as aloudspeaker.

' For flash tuning, the dial l i may be constructed to selectively receive a plurality of tabs Ma, lib, He, etc., at various positions on the dial at which flash stations are received, as indicated by the pointer l2, and each tab carries the call letters of the particular station received at that dial setting. In addition, the flash control apparatus may be in'the form of a dummy dial or comb l3, and a dummy ,rlointer l carryinga spring finger L la, relatively movable with respect to each other and synchronized with the dial and pointer, and

v with the flash lightarm lea upon which apparatus the user may set up the adjustments to operate the :flash signal at'any desired dial settings. l

Carried by the dummy dial or comb there may be provided a number of adjustable contact fingers l3a, lSb,

justedto make contact with spring finger Ma carried by the dummy pointer I4- and thus to close a circuit between the comb and the spring finger at a numberof predetermined dial positions; 'I'heposition of the various fingers i311, b, c, etc, is selected to'correspond to the dial settings at which various selected flash stations are received, so that a circuit is closed between .position of the dial t ed upon an arm its whose synchronized with those of 'justed for flash tuning,

I30, .etc., arranged when ad-.

the dummy dial it. and spring finger Ida at each at which a flash station is one such position only for station, and the position of each flash received, there being each flash station being different from that of other flash stations, as will be understood.

When the circuit between comb and finger is closed at the position corresponding to that of a flash station, a circuit is operated'including the flash indicator, which may be a lamp l 6, mountmovements may be the pointer l2 and which may be shielded so as to illuminate only the particular tab bearing the call letters of the flash station which is received at that point.

Preferably, the apparatus is constructed in Ways which will be described in more detail hereafter, so that the receiver is mute, when adexcept when the signal selector or. tuning mechanism encounters a flash tuning station. When the circuit is closed between comb and spring finger, the flash indicator the receiver circuits lamp lii'is energized, and

give voice to the receiver, so that when a tab is illuminated to show being received, the loud the program of that particular station.

a particular flash station speaker will reproduce While the receiver is in a transition stage, be-

ing tuned away from one flash station to another, little or no response will be received from, other stations,or from static or noise, between the flash station positions. When the position for another flash station is reached, the flash indicator will light, and the receiver will be fvoiced. The circuits by which this is accomplished form particularly the subject of my invention.

Referring now more particularly to Fig. 2, 20 represents any suitable source of alternating current, which may for example be the house supply, in case the receiver is of the plug-in type arranged to operate from a house source of alternating current. It may, however, be any other suitable source of alternating current for operating a radio receiver, such as a buzzer converter used for automobile receivers, or other apparatus.

The alternating current is preferably fed to a transformer 21 having primary and secondary windings Em and 25b. From the secondary Zlb, one side of which is preferably grounded, a conductor leads to flash signal lamp it, which may travel around the dial l i in synchronism with the Lamplfi is connected to spring finger Ma, and

to one terminal of the primary 22a of a transformer 22, the other terminal of which may be grounded. Comb 63 may likewise be grounded. Lamp 33, if used, may be connected in shunt with winding 22a.

Thesecondary 22b of said transformer may have a considerably larger number of turns than its primary, in order to step up the voltage out put of said transformer. The output of said transformer may then be rectified, as for example, by'cathode ta and diode anode 6b of tube 6, and the rectified voltage applied as a muting bias to the radio frequency, intermediate frequency, and audio frequency amplifier tubes of the receiver.

Included in the circuit with secondary 22b and The rectification herein shown as performed by tube may be performed by any desired type tube which will rectify alternating current, such as a diode provided for the particular purpose. However, it may equally well be, and preferably will be, one of the tubes provided for other purposes in the receiver, if it has a diode anode electrode not otherwise used.

By way of example, I have shown it as a tube of the type known in the art as a duplex-diodetriode which is employed in the receiver in this instance as an audio frequency amplifier. This tube may comprise cathode 6a, diode anodes 6b and 60, control electrode 611 and anode 6e.

If diode anode 6b is not being used for any other purpose, it may be employed as the rectifier anode for the purpose of this invention, without interfering with the operation of the remaining electrodes of the tube for their own purposes.

The rectified voltage may be supplied through resistances 23 and 29 to the various grids of the tube to be over-biased for muting operation, which may be the radio frequency, the intermediate frequency, and the audio frequency amplifier tubes or either or all of them. By-pass condenser 21 may be provided across resistance 26 to insure that all, or substantially all alternating currents are removed before the voltage is applied as a bias voltage. For example, the muting overbias voltage may be applied through resistance 28 to the control grid 1c of audio frequency amplifier tube 7 and to the suppressor grid 2d of the radio frequency amplifier tube 2, and through resistances 29 and 30 to the control grid 6d of the audio frequency amplifier tube 6. and through resistance 29 to the suppressor gr d 4d of the intermediate frequency amplifier tube 4. It will be noted that the connection supplying the overbias to suppressor grids 2d and id is in place of the customary connection of the suppressor grid to the cathode of the same tube.

The operation of the system is as follows: when the receiver is turned on, and is in an intermediate position, no receiving a flash station, current is drawn by transformer primary 2|a and supplied to the secondary Mb. The secondary current flows through the filament of flash signal lamp l6, and through the primary 22a to ground. The impedance of transformer primary 22a is so related to the remaining impedance of the circuit that most of the voltage drop occurs in the said transformer primary, and the filament of lamp I6 is not illuminated and the voltage drop across winding 22a keeps lamp 33 lighted. Lamp IE will preferably be a low voltage, or heavy current lamp, while 33 is higher voltage or lower current lamp.

Under such conditions, secondary 22b draws current, and the turns ratio of this transformer is chosen to supply to its associated rectifier a sufficient voltage, which when rectified and applied to the control grids of the tubes to be muted, will over-bias them to the point of substantially no response.

When a fiash station is tuned in, as will be seen, contact is made between spring finger Ma and one of the projections from comb l3, to ground, short-circuiting secondary 22b and. lamp 33. This increases the voltage across the filament of lamp [6, so that it is then lighted and 33 extinguished. At the same time, current ceases to flow through secondary 22b and no current is rectified by tube 6, and hence there is no voltage developed across resistance 26, and the tubes to which an over-bias was previously applied for muting purposes no longer receivesuch over-bias, but take their normal operating potential and operate in the normal way to amplify the voltage supplied to them. I

When the station selector is operated to tune out the flash station to which the receiver was responding, contact between the comb l3 and spring finger Him is interrupted, primary 22aagain draws current, and the'system operates to supply an over-biasing voltage to the muted tubes as already described.

While I have shown and described certain pre ferred embodiments of my invention, it will be understood that modifications and changes may be made without departingfrom the spirit and scope of my invention, as will be clear to those skilled in the art.

I claim:

1. In a flash tuning radio receiver, in combination, a source of alternating current, an indicating lamp in series therewith, a relatively high impedance path in series therewith, a rectifier associated with said high impedance path, means for applying the output of said rectifier, to at least one tube of said receiver as a muting bias, and means for completing the circuit of said alternating current'source through said lamp exclusive of said high impedance path.

2. In a flash tuning radio receiver, in combination, a source of alternating current, an indicator lamp in series therewith, and a relatively high impedance path in series therewith, a rectifier associated with said high impedance path, means for applying the output of said'rectifier to at least one tube of said receiver as a muting bias, and means for completing the circuit of said alternating current source through said lamp exclusive of said high impedance path, said means comprising stationary and movable contacts relatively movable in synchronism with the signal selector of said receiver.

3. In a fiash tuning radio receiver a single contact control system comprising, in combination, an indicating lamp for indicating the adjustment of flash tuning stations, a source of alternating current for energizing said indicating lamp, and having a transformer primary and secondary associated therewith, a rectifier associated. with said secondary and having its output applied to at least one tube of said receiver as a muting bias, and a pair of contacts movable relatively to each other synchronously with the signal selector of said receiver for short-circuiting said transformer primary. 1

4. In a flash tuning receiver, a single contact control system comprising, in combination,'an

, indicating lamp for indicating the dial adjustment of flash tuning stations, a source of alternating current for energizing said indicating lamp, a transformer having its primary in series with said indicating lamp, and having a secondary associated therewith, a rectifier associated with said secondary and having its output applied to at least one tube of said receiver as a muting bias, a circuit for short-circuiting said transformer primary, said circuit comprising a movable contact synchronized with the signal selector, and a plurality of contacts to be made by said first contact at dial positions, at each of which one of a group of previously selected transmitting stations is received.

5. In a flash tuning radio receiver, in combination, a source of alternating current, a flash signal lamp in series therewith, a transformer having primary and secondary windings in series with said source and said lamp, the impedance of said primary being sufliciently high to prevent illumination of said lamp when current is fiowing through said transformer primary, a rectifier associated with the secondary of said transformer, means for applying the output of said rectifier to at least one tube of said receiver as a muting bias, and means operable synchronously with the signal selector for short-circuiting said transformer primary at tuning positions of flash stations.

6. In a flash tuning receiver of the superheterodyne type, comprising at least one radio frequency amplifier tube, in combination, a source of alternating current, an indicating lamp in series therewith, a relatively high impedance path in series therewith, a rectifier associated With said high impedance path, means for applying the output of said rectifier to said radio frequency amplifier tube as a muting bias, and means for completing the circuit of said alternating current source through said lamp eX- clusive of said high impedance path, said means comprising stationary and movable contacts relatively movable in synchronism with the signal selector of said receiver.

7. In a flash tuning receiver of the super-heterodyne type, comprising at least one radio frequency amplifier tube having a suppressor grid, in combination, a source of alternating current, an indicating lamp in series therewith, a relatively high impedance path in series therewith, a rectifier associated with said high impedance path, means for applying a direct current voltage from the output of said rectifier to the suppressor grid of said radio frequency amplifier tube as a muting bias, and means for completing the circuit of said alternating current source tl'irough said lamp exclusive of said high impedance path, said means comprising stationary and movable contacts relatively movable in synchronism With the signal selector of said receiver.

8. In a flash tuning receiver of the superheterodyne type, comprising at least one intermediate frequency amplifier tube, in combination, a source of alternating current, an indicating lamp in series therewith, a relatively high impedance path in series therewith, a rectifier associated with said high impedance path, means for applying a direct current voltage from the output of said rectifier to said intermediate frequency amplifier tube as a muting bias, and means for completing the circuit of said alternating current source through said lamp exclusive of said high impedance path, said means comprising stationary and movable contacts relatively movable in synchronism with the signal selector of said receiver.

9. The combination claimed in claim 8, in which said intermediate frequency amplifier tube includes a suppressor grid, and means for applying said direct current voltage from the output of the rectifier to said suppressor grid as a muting bias.

10. In a flash tuning receiver of the super heterodyne type, comprising at least one radio frequency amplifier tube and at least one intermediate frequency amplifier tube, in combination, a source of alternating current, an indicating lamp in series therewith, a relatively high impedance path in series therewith, a rectifier associated with said high impedance path, means for applying a direct current voltage from the output of said rectifier to said radio and intermediate frequency tubes as a muting bias, and means for completing the circuit of said alternating current source through said lamp exclusive of said high impedance path, said means comprising stationary and movable contacts relatively movable in synchronism with the signal selector of said receiver.

11. The combination claimed in claim 10, in which said radio and intermediate frequency amplifier tubes each include a suppressor grid, and means for applying said direct current voltage from the output of the rectifier to said suppressor grids as a muting bias.

INNOKENT N. VORIE. 

